<template>
  <el-select
    v-model="valueTitle"
    placeholder="请选择"
    :clearable="clearable"
    @clear="clearHandle"
  >
    <el-option :value="valueTitle" :label="valueTitle" class="options">
      <el-tree
        id="tree-option"
        ref="selectTree"
        :accordion="accordion"
        :data="options"
        :props="props"
        :node-key="props.value"
        :default-expanded-keys="defaultExpandedKey"
        @node-click="handleNodeClick"
      >
      </el-tree>
    </el-option>
  </el-select>
</template>

<script>
export default {
  name: 'el-tree-select',
  props: {
    // 配置项
    props: {
      type: Object,
      default: () => {
        return {
          value: 'id', // ID字段名
          label: 'title', // 显示名称
          children: 'children', // 子级字段名
        };
      },
    },

    // 选项列表数据(树形结构的对象数组)
    options: {
      type: Array,
      default: () => {
        return [];
      },
    },

    // 初始值
    value: {
      type: String,
      default: () => {
        return null;
      },
    },

    // 可清空选项
    clearable: {
      type: Boolean,
      default: () => {
        return true;
      },
    },

    // 自动收起
    accordion: {
      type: Boolean,
      default: () => {
        return false;
      },
    },
  },

  data() {
    return {
      valueId: null,
      valueTitle: '',
      defaultExpandedKey: [],
    };
  },
  mounted() {
    (this.valueId = this.value), // 初始值
      this.initHandle();
  },
  methods: {
    // 初始化值
    initHandle() {
      if (this.valueId) {
        setTimeout(() => {
          window.console.log(this.options);
          this.valueTitle = this.$refs.selectTree.getNode(
            Number(this.valueId)
          ).data[this.props.label]; // 初始化显示
          this.$refs.selectTree.setCurrentKey(Number(this.valueId)); // 设置默认选中
          this.defaultExpandedKey = [this.valueId]; // 设置默认展开
        }, 500);
      } else {
        this.valueTitle = '';
      }
      this.initScroll();
    },

    // 初始化滚动条
    initScroll() {
      this.$nextTick(() => {
        let scrollWrap = document.querySelectorAll(
          '.el-scrollbar .el-select-dropdown__wrap'
        )[0];
        let scrollBar = document.querySelectorAll(
          '.el-scrollbar .el-scrollbar__bar'
        );
        scrollWrap.style.cssText =
          'margin: 0px; max-height: none; overflow: hidden;';
        scrollBar.forEach((ele) => (ele.style.width = 0));
      });
    },

    // 切换选项
    handleNodeClick(node, obj) {
      window.console.log(obj);
      // if(obj.level <= 1 ) return false
      this.valueTitle = node[this.props.label];
      this.valueId = node[this.props.value];
      this.$emit('getValue', [this.valueId, this.valueTitle]);
      this.defaultExpandedKey = [];
    },

    // 清除选中
    clearHandle() {
      this.valueTitle = '';
      this.valueId = null;
      this.defaultExpandedKey = [];
      this.clearSelected();
      this.$emit('getValue', [this.valueId, this.valueTitle]);
    },

    // 清空选中样式
    clearSelected() {
      let allNode = document.querySelectorAll('#tree-option .el-tree-node');
      allNode.forEach((element) => element.classList.remove('is-current'));
    },
  },

  watch: {
    value() {
      this.valueId = this.value;
      this.initHandle();
    },
  },
};
</script>

<style scoped>
.el-scrollbar .el-scrollbar__view .el-select-dropdown__item {
  height: auto;
  max-height: 274px;
  padding: 0;
  overflow: hidden;
  overflow-y: auto;
}
.el-select-dropdown__item.selected {
  font-weight: normal;
}
ul li >>> .el-tree .el-tree-node__content {
  height: auto;
  padding: 0 20px;
}
.el-tree-node__label {
  font-weight: normal;
}
.el-tree >>> .is-current .el-tree-node__label {
  color: #409eff;
  font-weight: 700;
}
.el-tree >>> .is-current .el-tree-node__children .el-tree-node__label {
  color: #606266;
  font-weight: normal;
}
</style>
